1. Field of the Invention
The present invention relates to products, systems, and methods for controlling coleopteran, including, among others, Hypothenemus hampei (coffee berry borer, CBB), the most economically important pest of coffee worldwide. More specifically, this invention relates to methods and systems for repelling coleopteran, for purposes of both population control and crop protection through the use of volatile semiochemicals with potent and varied behavioral effects. This semiochemical formulation can be employed in a broad range of means, including a monolithic repellent and repellent-impregnated rubber to be deployed in controlled areas, and a liquid formulation that can be amenable to spray application.
2. Background of the Invention
Chemicals existing within the environment that convey some form of information, known as semiochemicals, are used extensively by arthropods to communicate with each other and can be used in strategies for pest management.
The direct management of insect pests using semiochemicals for repellent approaches can provide excellent suppression of key coleopteran pests in agriculture and forestry. Large-scale implementation projects have yielded significant reductions in pesticide use while maintaining acceptably low crop-damage levels.
The coffee berry borer (CBB), Hypothenemus hampei, is the most economically significant pest of coffee worldwide, creating an estimated $500 million in losses annually. The beetle is native to Angola, however it extended its range throughout Africa during the early 20th century and has continued to do so since. It is believed that most invasions occur due to the importation of contaminated seeds, colloquially beans. Regardless of the mode of invasion, CBB has effectively extended its range to every major coffee producing country in the world, making landfall in the U.S. state of Hawaii in 2010.
The coffee industry has an estimated global economic value between $70 and $90 billion annually. Per pound retail prices for coffee can vary drastically depending on a variety of product parameters and the consumer market, for example per pound coffee prices within the U.S. market range from $2-$30 depending on the product. Due to these pricing variations the economic impact of CBB losses to some cultivars is substantially greater than others. When densities of CBB reach very high levels they can cause yield losses upwards of 35% with 100% of berries infested at harvest time, greater losses can occur if harvest is delayed. In addition to the direct loses, CBB damage can devalue coffee prices by 30-40%.
The CBB is such a destructive force in the coffee industry because the entire larval stage, and most of the adult stage, is spent within the coffee berry. Males never emerge from the berry, therefore the entire life cycle of a male CBB from development to mating is confined to the same coffee berry it hatched from. Female CBBs, on the other hand, remain within the coffee berry up until mating. Once mated, female CBBs attack immature and mature coffee berries. The attacking female bores a hole in the coffee berry and lays eggs amongst the seeds at a rate of 2 to 3 eggs per day for a period of 20 days. The larvae feed upon the seeds until they mature and mate, repeating the cycle. There is a 10:1 sex ratio favoring females; allowing for rapid proliferation throughout a coffee plantation. Further, as most of the life cycle occurs inside the berries, control strategies, both chemical and non-chemical, are greatly limited.
Because female CBB are able to fly and their lifespan allows for long durations of activity, (nearly six months under the correct environmental conditions) damage to developing berries can occur year round. Three types of damage have been reported due to CBB: 1) premature fall of young berries, 2) increased vulnerability of infested ripe berries to secondary infection, and 3) reduction in both yield and quality of coffee, reducing the profitability of the crop.
Historically, coffee farmers have relied on Endosulfan for the control of CBB, but as of April 2011, it has been phased out globally. Endosulfan is a highly toxic chemical that poses significant risk to human health by acting like an endocrine disruptor. It also poses high potential for bioaccumulation, which can negatively impact entire ecosystems surrounding coffee plantations. Further, CBB's life cycle makes it nearly inaccessible to most control measures. Coffee farmers have been left in an extremely difficult position where they must combat CBB with insecticides that have not yet been evaluated for effectiveness against CBB or labeled for use in coffee. Most insecticides used to date have proven ineffective for control of CBB.
Mycoinsecticide control products containing the spores of the fungus Beauveria bassiana, such as the EPA registered BOTANIGARD® ES (BioWorks, Victor, N.Y., US), have demonstrated the ability to reduce female oviposition rates and larvae production and increase CBB mortality. However, the product requires two separate applications, one mid and one late season, directly to the berries and surrounding ground cover, increasing planning and logistical requirements. Additionally, the product costs $60-$90 per acre per application, making overall protection costly.
Alternatively, coffee farmers can employ various cultural control or hygiene approaches to reduce CBB populations within the plantation: removal of berries and trapping prior to and during fruit development, contained harvesting, and post harvest plantation sanitation.
Pruning fruit-producing trees is a necessity in maintaining a healthy and effective growth operation. Two methods of pruning exist within coffee farming: 1) pruning one or two verticals on the tree each year (the Kona method), or 2) pruning all the verticals on the tree in the same year every three to five years (the Beaumont-Fukunaga method). However, prior to pruning, any berries on the trees must be removed to ensure that they do not fall to the ground. Research has indicated berries not removed before pruning can result in as many as 3.2 million immature and adult CBBs per acre. Further, the CBBs within the berries remained reproductively active and continued to emerge for up to three months after being on the ground. In order to minimize the risk of existing populations continuing into the next season, all berries removed prior to pruning must either be buried or burned.
Coffee has a prolonged and variable fruiting season, flowering depends on several environmental conditions, berry growth is slow, and all berries do not ripen simultaneously. This poses an on-going challenge for coffee farmers attempting to intercept female CBBs as they emerge from their birth berry and seek out a new, uninhabited host berry. Traps, such as the BROCAP® (CIRAD, Paris, FR), can be installed at a rate of 8 per acre and suspended from the coffee tree at 1.5 m. Traps necessitate a lure composed of methanol and ethanol mixed to various ratios. Baited traps do not guarantee the removal of the CBB from the field, although at sufficient trap density protection can be achieved. More often traps are used in an effort to monitor for the presence of the beetle in the field.
During harvest, emphasis is placed on removing all ripe and dropped fruit. Harvest bags should be tied shut at harvest to avoid the escape and dispersal of CBB. The processing of berries to seeds should be performed in closed or semi-closed structures to prevent the escape of CBBs and allow for proper disposal. Additionally, during post harvest, dried and dropped berries should be collected from the field and buried or burned as they were at the beginning of the season.
There may exist alternative and/or more effective methods to control CBB. CBB, like most beetles, uses chemical signaling systems to determine many aspects of its life cycle. Semiochemicals, artificially or naturally sourced, can be used to influence these chemical pathways. One common function of these semiochemicals in beetle populations is repellency; communicating to incoming beetles that a particular host is overpopulated and no longer suitable for colonization.
CBB is a bark beetle and member of the sub-family Scolytidae. This sub-family includes a genus of beetles, Dendroctonus, that are well known major pests to global timber industries and as such have well researched and documented semiochemical communication systems. One semiochemical, verbenone, has shown to be strongly repellent to the Dendroctonus genus and may be strongly repellent to the entire Scolytidae sub-family.
Prior studies have shown that on average, CBB chose to travel down a path not containing verbenone. In these experiments a Y-tube olfactometer was used to force CBB to travel one of two paths in order to elucidate what impact, if any, specific semiochemicals, known to influence the behavior of other bark beetles, have on CBB. The results confirmed that verbenone is unattractive to CBB and can potentially be correlated, but not confirmed, to have a repellant effect. However, the study did not provide any specific information on the dosage or verbenone type used.
What was not previously known, and has been now discovered, is that exposure to (1S)-(−)-Verbenone (cas #1196-01-6), as well as other verbenone enantiomers will cause both male and female CBBs to dislodge from the coffee berry. The invention herein pertains to use of all potential verbenone sources, including synthetic sources, natural sources or any natural extract containing verbenone for the use of repelling or otherwise modifying the behavior of Hypothenemus hampei, the coffee berry borer. The present discovery applies specifically to the amount of verbenone, including all verbenone enantiomers, required to achieve such repellency. Applications of 1-10,000 g of verbenone (Active Ingredient, A.I.) per acre, using wax emulsions or any other field application technology, will be sufficient to repel CBB from a coffee field.
Verbenone has been discovered to be an efficacious repellant to CBB within a coffee plantation. The repellent effect will be used to push CBB from a currently infested plantation, decreasing or potentially removing the infestation within the application area. The technology disclosed herein may also be used to repel CBB and prevent its establishment in low or non-infested plantations, such as new plantings, aggressively controlled areas or geographic regions where CBB has not entered.
Another aspect of the presently disclosed invention is the use of verbenone as an accessibility tool. By repelling CBB from the coffee berries, CBB becomes accessible to insecticide sprays. Such an increase in accessibility will lead to more effective insecticide regimes and to a more efficient use of such insecticides.
It is believed that that 1-2,500 verbenone point sources per acre, using monolithic or any other field application technology, will provide effective repellency to CBB.
Based on the considerations above, verbenone acts as a suitable CBB repellent when formulated with the Specialized Pheromone and Lure Application Technology (SPLAT) described in U.S. Pat. No. 7,887,828, the entirety of which is incorporated by reference herein. This formulation for Coffee Berry Borer of the present invention (coined SPLAT Verb, and used as such herein) has a strong repellent effect on adult CBB, at low, economically viable doses; it is produced commercially and in large quantities, is labeled organic and registered for “all crops”; and it is a stable molecule (once UV-protected and anchored by SPLAT).